The molecular lesion of sickle cell anemia is the polymerization of sickle hemoglobin which is dependent on the proportion of sickle and non-sickle (normal adult or fetal) hemoglobin in the red cell, the corpuscular hemoglobin concentration and the oxygen content. To study the relationship between hemoglobin S polymerization within the intact erythrocyte and cell rheology, we use a ball microrheometer designed to measure the viscosity of as little as 20 microliters of sickle red blood cell suspensions. Studies of erythrocyte suspensions from sickle trait (AS) and sickle cell (SS) blood in autologous plasma and saline demonstrate that viscosity and intracellular polymer formation are linearly related up to a polymer fraction of 55% and that viscosity profiles of red blood cell suspensions depend primarily on hemoglobin polymerization. Preliminary data also suggest that a non-linear increase in viscosity due to cell dehydration can be observed. Such measurements of viscosity of red cell suspensions should be useful in evaluating the effects of pharmacological agents designed to directly affect hemoglobin polymerization within the intact cell by direct modification of the hemoglobin or red blood cell, or by changing the proportion of sickle and non-sickle hemoglobins. To supplement the therapeutic approachs for hemoglobinopathies, particularly sickle cell anemia, we have considered the use of ribozymes to decrease the mutant hemoglobin molecule. When used in combination with strategies designed to introduce the production of normal globin genes, the ribozyme can be used to maintain the chain balance between the alpha- and beta-like globin chain production and the overall hemoglobin per cell. A multiribozyme construct using hammerhead ribozyme sequences targeting several sites on the alpha-globin mRNA has been successfully introduced into K562 cells to supress alpha-globin specific production. In our efforts to produce an animal model for sickle cell disease, we are using embryo transfer after injection of DNA containing expression constructs for the human alpha- and beta-S-globin genes linked to the globin locus control region in eggs harvested from the Panepinto miniature swine. We have now demonstrated that progeny can be obtained from such manipulations, although transgene incorporation remains to be achieved.